Any discussion regarding sex or gender issues must first consider just what allowed this discussion to even be possible in the first place. Unlike certain basic organisms, humans, like many other animals, have a genetic system that defines sex in its own way, regardless of what our culture or society does. The human genome may be the most remarkable entity that exists in this entire universe, not only for its complexity, but also its ability to provide a framework for the person each of us is today.

In starting with the basics, all human beings, with the exception of those who have abnormal genetic conditions, have exactly 23 pairs of chromosomes. The first 22 are called autosomal chromosomes, and are homologous with each other, which basically means they have the same size, structure and position. The first autosomal pair is the longest; the 22nd pair is the shortest. Meanwhile, the 23rd pair is called allosomes, or sex chromosomes. They differ from autosomes in many ways, one of which is that for males, the pairs differ in size and shape.

Allosomes determine sex in the human species, and all sex characteristics in males and females are initiated by genes on the 23rd chromosome pair. Males have an XY pair; females have XX. All human beings inherit an X chromosome from their mother, and it is the father who determines the sex of the child. If the father contributes an X chromosome, then the child will be a female. If the father contributes a Y chromosome, then the child will be a male. Once the child is conceived, either male or female, then every single somatic cell in the human body gets a copy of the sex chromosomes. Interestingly, the X chromosome has about 1,000 genes, roughly 10 times more than the Y chromosome. Not all genes on the X chromosome are related to sex characteristics. Most are actually associated with other traits or conditions. In fact, some conditions such as hemophilia or color blindness, are called X-linked. On the contrary, the Y chromosome is much smaller in size, and many of its genes have to do with other items besides physical sex characteristics, such as sperm production and health-related factors. Just one gene on the Y chromosome, the SRY gene, is responsible for male anatomical traits. When this gene is compromised, it can lead to disorders of sexual development (DSD) in men. Not all vertebrates utilize an XX or XY system as mammals do. Some birds, reptiles and even insects use a ZW system that is somewhat opposite of what we see in humans. Males have two of the same chromosomes (ZZ) and females have differing pairs (ZW).

It is easy to get lost in the complexity of the genome system, but in reflecting on it, there are also remarkably simple aspects of it that seem important to consider. First, whereas all of the characteristics of the human person, such as height, bone structure, temperament, eye color and functionality, are determined across the chromosomes, one is not. That one characteristic is the anatomical features that determine sex and reproduction. No matter how you conceptualize the origin of the human makeup, it is curious to consider that its design clearly put a premium on differentiating these features. Just like any other trait or feature, anatomical features of sex could have been initiated from various chromosomes. But instead, X and Y appeared, unlike all other pairs of chromosomes, and made it clear that men and women were created distinct just as their chromosomes that initiated their differences were. In the thousands of pages I have read on the transgender topic, it surprises me that no one has taken the time to consider the potential message of this genetic reality. Furthermore, it is interesting to note that the father “determines” the sex of child, obviously not by some conscious choices, but certainly by an unconsciously anatomical one. The sperm pursues, the egg waits. And yet at the same time, it is the X chromosome, the legacy of our mothers, that carries a huge amount of genes.

All of this is relevant because the discussion of gender often starts with the phrase “sex assigned at birth.” But in reality, sex was defined at conception, and no one in the scientific world disagrees with this idea. Our genome leaves no equivocation. Of course, how we ultimately feel and express our gender leads to much other discussion. But I would suggest the phrase uttered by Simone de Beauvoir, "One is not born, but rather becomes, a woman,” often utilized as a rallying cry for the transgender movement, is both true and not true. She (in the broad sense of the word,) except in cases of DSDs, is born a female and does not become one. However, she is born as a girl, and becomes a woman, in however she ultimately expresses this. But her genes don’t lie. Neither do the physical features that are part of the phenotype of our genes in spite of exceptions that may emerge. For starters, there are obvious sexual anatomical differences that are apparent at birth and in puberty (e.g., penis vs. vagina, chest vs. breast) that lead to starkly different roles when it comes to conception, gestation and early child rearing. From there, men have Adam’s apples (excessive protruding cartilage around the voice box) and larger voice boxes altogether (thus the deeper voices). Men have a much greater concentration of hair all over their body, and the ability to grow beards. Women generally have half the strength of men in the upper body and two-thirds in the lower half while women and men also store their fat differently; men also typically have greater bone mass and a lower percentage of body fat. Yet these familiar sex differences are only the beginning.

The American Physiological Society (APS) notes even further distinctions as part of its recommendations for basic medical curriculum. In addition to sex hormone differences and starkly different rates of transmission for a number of sex-linked diseases, differences exist in most organ systems. For example, men have wider airways and larger lungs even when height is accounted for, and have larger left-ventricular mass and chamber size in the heart. Women have a higher resting heart rate and lower resting blood pressure. Well-defined structural differences in the brain have been documented that work in concert with sex steroid hormones that lend themselves to distinctly male versus female practices. As noted in the article "When Is a Sex Difference Not a Sex Difference?" (pg. 85), “For neuroendocrinologists, there is no debate on whether there are sex differences in the brain, including humans. The obvious sex differences in reproductive physiology; females ovulate on a periodic and regular basis, get pregnant, deliver, and lactate, and males do not, necessitate that the brain regions regulating these diverse profiles be different.” Collectively, these are just a few of the many sex differences that exist outside any socialization or psychological factors that may be discussed as driving gender.

Of course, exceptions can exist. But what genetics and biology teaches us is that men and women are not created equal in function and structure although equally deserving of dignity and respect. Yet in regards to the ideas of gender mainstreaming and non-binary identification, the lesson of biology and genetics is that these ideas come with great risk. Just as any revolt against our biological makeup carries many potential consequences, so it seems that a clash between sex and gender carries the same inherent peril on an individual and global scale. The science of gender identity lags far behind the science of sex identity, yet worldwide, many seem ready (or have already begun) to move forward with gender-based ideas of identity without having the scientific framework to do so.

On this note, I close out this series with a few simple reflections of my own:

I have no doubt that men and women have had cross-gender feelings and identification since the beginning of time and that a select few were born with disorders of sexual development (DSDs). We as medical community need to find a more scientific, compassionate means of working with all who are afflicted with a DSD from the point it is identified.

I have no doubt that various societies have long been guilty of restricting men and women to specific modes of gender expression and gender roles. We need to continue to identify how this affects people and understand how deeply held values and beliefs can also co-exist while not unfairly “confining” men and women.

I have no doubt society has long abused, disrespected, discarded, discriminated and disenfranchised those who do not adhere to typical gender roles. We all must continue to address these travesties when they occur but also why they occur (in understanding the full picture).

I have no doubt that both innate and cultural factors influence how people identify as males and females.

Yet, I have serious concerns that identifying as transgender or non-binary is a healthy alternative for which anyone can or could aspire.

I have serious concerns that we as a society should be supporting transgender or non-binary identity as a cultural ideal instead of doing everything possible to promote the healthiest alternative, that is, aligning gender with sex.

I have serious concerns that in our noble attempt to empathize and address sexuality issues that are not “mainstream” or “majority,” we may be (intentionally or unintentionally) undermining practices and values that provide a core basis for our society as a whole.

I know we can do better for all people in regard to sex and gender issues if we put aside the politics of divisiveness and ideology that hamper sincere efforts to improve understanding and outcomes.

As a psychologist, I am charged with empathetically treating each person I see with the best information and practices that exist. Similarly, as a society, we must adhere to the best practices and knowledge that we have in the midst of a complicated, unclear landscape. And for as long as humans have existed, even in situations of gender nonconformity and cross-gender expression, our genes and our bodies remain the best guides we have. Until this changes, it is critical that we as a society do not abandon what we know to be true for what feels to be true even as in our offices we discern what is best for each individual. History has taught us repeatedly that when we do, dire consequences result. Do we dare ignore this lesson again?

I began this series with an acknowledgement of the sensitivity of the matter at hand and my goals in addressing this topic. Yet having read the entire series, some of you may find yourself angered about various information, beliefs or ideas I have put forth. You might find yourself feeling that I, as a mental health professional, am once again utilizing my position and perceived “authority” in a way that is not helpful or is even harmful to individuals and the population as a whole. Frankly, this reality is one of the reasons that I most dislike being a writer or speaker on difficult matters such as this; no matter what I say or do, I realize each person will form their own opinions, sometimes negative, about what I say. But just like you, I must adhere to two universal goals I believe we should all embrace. One, to seek out and pass along the best information available. Two, to be honest, in a respectful manner, regarding the thoughts, feelings, and beliefs I have while always seeking to grow and learn in both areas. I have worked really hard to do this here, and I ask that you the reader, my neighbor, considering aspiring to the same two principles. If this happens, and we come together in this way, I am certain the outcomes for all will be much better than we could have imagined.

A few weeks ago, our seventh child, Samuel Augustine, was born into this world. Helpless as can be, his arms extending upward and his cries echoing in the early morning hours throughout our home, I could not help but be once again reminded that the only thing that matters is what is truly best for him. He knows nothing of agendas or politics or religious affiliation, but he is hungry for what feeds and fills him, and desiring of the sounds and touch that comfort and soothe him. I am 40 years older his senior. But it dawns on me that just as I want these things for him, I desire them, too. I owe it to him and his siblings to go search in what is real and good. And we really owe this to each other. He, like all of my children, will ultimately make his own decisions when he gets older. But in the meantime, it is up to me and his mother to pave a pathway of knowledge and discernment that helps guide him to the healthiest decisions he can make. I ask you to join us in this way.

James Schroeder is a husband and father of seven children and a pediatric psychologist. He is the author of three books that can be found on Amazon: “Wholiness: The Unified Pursuit of Health, Harmony, Happiness, and Heaven,” “Into the Rising Sun” and “Forty Days of Hopeful Prayer.” Send comments to jimandamyschroeder@gmail.com.